Draft control



Oct. 9,- 1951 w. G. JOHNSON DRAFT CONTROL Filed Nov. 28, 1947 INVENTOR.

WILLl AM donnson Y Avronucv Patented Oct. 9, 1,951

UNITED PATENT OFFICE v 2,570,553 j e Y Dann: ooNTRoL l 'William @Johnson irrilwatrkawis,

Application'Npyember 28, 13147. Striano. V"fjsfilis This invention relates to improvements '1in draft controls `for furnaces and :particularly "to controls: `which will automatically lclose fthe damper and check the furnace after a predetermined'lapseoftime. l 'Manyhomes employ hand-fired furnaces 'the drafts of "which are controlled vby chains 4or-other motion transmitting iconnectors'or Adraft Amanipulating devices' which 'lead from the basement 'to the first licor. 1t is the practice -to Ycharge Ethe re pot-of theinrnace `with fuel and then open the draf-ts Eby raising *the control chain or iconnector. This opens the draft in the ash `pit door and closes the check draft establishing vthe draft through the 're `jpotl Often the householder j'forgets about llt-he opening Vof ,the ldrafts and leaves the house unattended with 'the drafts f-ully open. The vunchecked re l'will soon burn at a high rate Vand overheat the entire heating system, creating -a ffi-re haZa-rd. Even though no extraneous fire results from such overheating, the lfire will usually burn itself out 'and the householder upon his'return will have to build a new re. A

It is, itherefore, anobject of this invention to provide a draft control which will automatically close the draft "after a predetermined lapse of time.

Another object of thefinvention vis to provide a draft control which may be easily installed lin the draft control chains or connectors of existing heating lsystems without change to `the {devices lfor manipulating such chains and lconnectors and holding Vthem .in lfully -open or closed position or selected positions therebetween.

- AA still further obiiect of this invention fis to provide a draft control which is simple and economical to manufacture. v f

These objects are attained by VVprovidingaunit comprising an--e1ongate'd-cylinder'in which a-piston is Imovable Abetweenpredetermined adjustable limits 'of fully contracted and fully extended positions, its movement I*for a portionV of l"its-stroke from contracted to extended position being yrestrained and f'slow lfand-for the Jbalance -of such stroke being unrestrained Iandrapid, and't's movement toward contracted position vbeingmunrestrained 'and-rapid, and lby connecting such unit between "sections VVof the 4dra/ft control rchain Lor other motion `.transmittingconnector. VYWhen the draftv control chain U`or connector is raised, the entire unit Ais raised and the draft opened. The weight of the dra-ft then causes -fthe unit to VJslowly elongate for apredetermined .dist-ameland thereafter ftolrapidly Jelongalte. keeps the draf-t 1ClatmS. (01.267-1).

open'for 'a predetermined time and then accom-j plis'hes '-a complet-e closing of the draft fat the en do'f such itime. "Whenthe draft control chain or `connector is reset to closed position, the 4unit rapidly collapses to its fully contracted length. The unit installed by merely removing a section-oftheyetieal run 'of the 'draft control chain or-other motion transmitting connector Vand substituting the unit for such Lsection by connecting the piston and the cylinder respectively lto the ends off-the adjacent J,sections so created. -Suoh substitution requires -no :change the exciting indexing V-in echan'isrns of the `draft :manipulating device. 1rli-terbeing initially adjusted, the safety operationwof Athe control is entirely automatic,` Iteriesets itself -withont vany 4attention `fromk the furnace operator Vever-y :time vthe draft manipu-y lating 'device or `rindexing #mechanism is moved to closedlpos'ition.

"The L novel ffeatures, which yare considered `characteristic @of ithevinvention, are .set forth with particularity lin s'the y'appended claims. 'The in vention itself, howevlerflboth as to its organiza*- tion and -its method of operation, together with additional obiects and ,advantages thereof, will best `be :understood from the 'following description of -a specific embodiment vwhen read 'in-cone nectifon with fthe accompanying drawing, which;`

Figs. l, `2, 'and 53 lare diagrammatic views `of a furnace with ia' draf-t lcontrol embodying the in- Verition v'installed iin the draf-t .manipulating -device, each `view illustrating Avarious positions of the drattfas will ibe hereinafter Vmore fully Idescribed; Y

-Fig. f4 is a sectional View fand Figs. `5 @and v'6 are views partly in plan fand partly .i-n sectionof a draft .control unit .fen-ibodyfing the invention, each 'view illustrating various positions of the parts yofthe-control as moreV particularly .desoribedherei-n; and Y Fig. "7 ya-fs'ectiona'l i-v'iew ltafken on 'the -lin'e 1 1 ofiFie'.

Referringto `the fdrawings by reference nu` morals, 'the draft vcontrol y`Unilift, generally designated D, is connected fin the Vertical run of a draft @control fchain lfl, the v`operation `of which opens '-aind `-iclosesthe `draft |12 of a .furnace i28. Anystandard indexing mechanism (not shown) may be Eutilized to imove *the chain lIl `fromthe closed positionland 'secure Vlit in the open 'positionfshown in Fig. '-l.V The unit Nl, however, may 'be "installed in other lmotion transmission con` nectors =or Adraft manipulating devices, such as flexible lwires, rods', -`orf-"the like. To install lthe unit I in existing controls it is only necessary to remove from the manipulating device a section substantially equal to the length of the unit when fully collapsed and inserting the unit in lieu of such section and connecting it to each of the ends of the adjacent sections created by the removal of Such section. It is, of course, preferable to install the unit in the vertical run of such manipulating device. However, the section where the unit is installed mayvary considerably from the vertical vso long as the liquid medium does not flow from the cylinder I3. In

some installations it may be necessary to install i in the manipulating device above the unit a stop ring or other abutment (not shown) which will limit the extent of the openingm'ovement of the manipulating device soth'at the draft I2 will not be opened a greater amount'tlian will be offset by the subsequent extension of the unit I0...

to fully extended positionj. One of the elements ofthe draft controldl! isa-hollow cylinder I3. The cylinder I3 is open at the'top and closed at the bottom. It is sufficiently long to permit of enough relative movement between Alt and the piston I4 to allow the draft I2 to close when the unit moves from the contracted position shown in Fig. 4.- to expanded position shown in Fig. 6. The piston I4 consists of a hollow cylinder open at both ends and provided with a ball type check valve 20. The opening through the piston provides a by-pass I5. The piston I4 has a loose t in the cylinder I3 and ismovable from the adjustable fully contracted position shown in Fig. 4 to the fully expanded position shown in Fig. 6. Lugs I6 at the top of the cylinder I3 form an abutment for determining the fully expanded position. v The piston AI4 is provided With connecting rods I'I which extend from the upper end of the piston and project above the top of the cylinder I3.A The connecting rods I1 may be made of a single one piece of wirenbent in U shape to form a bridge I8 which extends across the upper end of the by-pass I to hold the rods tothe piston and to provide a vconnector for therretraction spring I9. The, use of tWD connector rods I'I provides ample operating space at the top of the by-pass I5 for` the ball valvegZ. The ball seats under the influence of gravity to form a check valve which freely opens when the piston I4 is moving toward contracted position and which closes whenever the piston I4 is moving toward the extended position.V The upper ends of the connecting rod I1 are secured to a disk 2I, the periphery of Awhich extends beyond the outer confines of cylinder I3. To the cap 2| there may be secured a tubular member 22 which loosely telescopically ts'over the cylinder I3 to provide a dust cap. ,Thecoiled tension retraction spring I9 telescopcally vfits with the by-pass I5 and is secured to `the bottom` of the cylinder I3. It continually urges the piston I4 toward contracted position. Eyes 23, attached to the bottom of the cylinder I3 and the disk 2|, provide the means for connecting the unit I0 to the adjacent sections of the manipulating device such as chain I I. A collar 2 4 slidably ts around the cylinder I3 and is maintained in selected adjustable positions thereon by the action of a winged nut threadedly mounted in such collar. The collar 24 provides anV adjustable abutment which limits the downward movement of the dust cap 22 with respect to the cylinder I3 and hence determines the fully contracted position of the piston I4. The adjustment of4 this position determines the length Y0f tmihat it .will keep the draft I2 open. A liquid medium of density and specific viscosity greater than air (at ambient temperatures) is carried in the cylinder I3 so that its level 2'6 lies substantially a-t the center of height of such cylinder. In practice light oils have been found practical. If other liquids are used the clearance between the piston and cylinder must be so proportioned to sufficiently restrict the flow of the liquid medium used to require a predeterminedtime to elapse during which theA piston I4 is moving toward extended position.

The principle of the operation of the control I0 is that the piston I4, in moving from fully contracted to fully extended position, must pass through two mediums, one of which is of greater density and viscosity than the other and which are separated 'along' a substantially horizontal planehpositioned between the extreme limits of relative travel of such piston and cylinder. During the time that the piston is traveling inhthe mediumof greater density'a'nd specific viscosity its movement will be retarded. However, when the piston emerges from that medium and starts to move in the medium ofY lesser density and specific viscosity its movement will be unrestricted and unretarded and therefore will move with greatly increased velocity. The purpose, of

course, is to keep the draft open for an extended; predetermined time and then to close it. The

greater velocity at closing creates enough force of momentum to insurera tight closing of the draft.

It has Vbeen found practical, where oil is onVrr mediumand air the other, to provide the cylinder I3 with grooves 2'I which extend downwardly from the top toa point substantially below the line of separation between thenmediums Oil has a' tendency to cling to` the'surfaces of the cylinder I3 and piston'rl4to maintain aseal even after a substantial portion of ,the piston I4 has moved Vabove lthe level of the oil. The effect of thefgrooves 2'I is tobreak'down this seal and'Y permit the piston I4 to freely move in thealf` after it has reached 4the intermediate position shown in Fig. l5. c

When the unit I 0 is installed as heretofore dee scribed in the manipulating device or chainml I,- the draft control operates in the manneras hereinafter described When. the indexing-mecha.-y nism (not shown) .is moved to the draft openV position, force is applied to therchain I! an'rdfit;A with the unit I0, is raised and the draft I2 movedto open position, This positionisdiagrammatically illustrated in Fig. V1. At that time the pistonV I4 andrcylinder I3 are inthe 'fully'contracted' position shown in Fig. 4;. This contracted position has been previously Adetermined and-set byv ferent localities andseasons and with the differ-- ences in the naturaluction of ,different furnaces. Immediately following the opening of the draftA I2, the weight of the draftj I2,Aorof a supplemen-H tal Weight (not Shwll);v if the draft does not' happen fto be suiciently heavy, will cause the cylinder I3 to moveV downwardly with respect to thevpiston I4 against the tension of spring 19; Such movemern;V takes place` only insofarv as the oiln or other mediuml selected vpasses through the spate :between the. .pistgngiiaarnswingend..

attuate riis'ffr greater than han or the 'beta1 travel" the' the center f the piston :I4 and the bottom of the piston Il has reached the bottoms of the grooves Z'I. At this time the oil lseal -is broken and the cylinder I3 starts to drop with rapidly 'accelerate ing speed. This speed greatly increases when-'the oil level has receded entirely'below the piston and?v the pis'ton'isl then moving freely through the air' r'bthe'r medium yof lesser density vand specific viscosity. Consequently, the `last*'ipa'rt dfi the stroke is accomplished with enough s'peed to force the `draft to a tightly plosed position. V'-.lllie piston Il and cylinder I3 are then in the lr'elati l tions illustrated in Fig. 6, the legs lli p even further movement. During -all Vofthese movements, of -course,-'theV spring I@ is stretched-by the weight of the cylinder 1 3, the lower section of chain I-I or other manipulating device, and draft I 2, and the control will stay in the position shown in Fig. 6 until the indexing mechanism for the chain I'I is moved to drafti iclosedp'ositin. When this occurs, the force on thech'ain II is removed and thewspring I9 draws the piston I4 and its associated parts down to the fully contracted position. During this 'movement the passage ofthe piston `I4 through the oil is unretarded f because the check valve 2D automatically opens. The control thus automatically resets litself in ""tl position illustrated in Fig. i4 and is then ready to repeat the operation when the Vindexing mechanism is again moved to draft open position.

l Although only 'one embodiment of th'e invention is shown and described herein, it will be understood that this application is intended to cover such changes or modifications as come within the spirit of the invention or scope of the following claims:

1. A draft control comprising an elongated'cylinder the top of which is freely open to atmosphere, a piston movable in said cylinder within predetermined limits, a liquid medium of density and specific gravity greater than air partly filling said cylinder to restrain and retard the movement of said piston throughout a portion of its travel in one direction through said liquid medium, a valve permitting the motion of said piston to be unrestrained by said medium in the opposite direction of travel of said piston, said piston being restrained by the atmosphere and unrestrained by said liquid medium in its travel v.

-above said liquid medium, and means for inserting said control in a draft manipulating device.

2. A draft control comprising an elongated cylinder closed at one end and open at the other end, a fluid medium in said cylinder and filling substantially the lower half thereof, the upper half being open to atmosphere, a cylindrical hollow piston loosely slidably mounted in said cylinder and movable between said ends, a ball valve resting on and adapted to close the upper end of said piston whereby said piston unrestrainedly moves downwardly through said medium, the movement of said piston upwardly through said medium being slow and retarded by the restricted passage of said medium between said cylinder and said piston until the level of said medium has receded a substantial distance past the top of said piston, the upward movement of said piston thereafter being rapid and unretarded, and means for connecting said piston to one section of a eran manipulating device and said' wundertean adjacent section of said draft dev e. j 1 3i A ldraft ycontrol comprising an elongated cylih'fei" closed ail-'one end ald open at 'the tithe? end, a uid'inediuin ifir said cylinder and filling substantially the lower half thereof, the upper half beingr `open to atmosphere, a cylindrical hollow piston loosely slidably mounted in said lcyl# iiider and movable between said ends, a ball valve re'sting'on and 'adapted to close the upper end of said piston whereby said piston unrestrainedly moves downwardly through said medium, the

movement o`f said piston upwardly through saidv rn iuin being slow and retarded byA the Viesiric'tet'l passagel of said medium between said cylinder and said piston lintilthe level of said medium has receded asubst'antial distaneepast the top osaid piston, the 'upward movement of said pistonthereafter being rapid and unretarded, means fo'' connecting said piston to one section cfa draft manipulating deviee and said cylinder toan de jaeent section of *sa-id 'draft dl'e'vice-y and l eens fr-fadustably limiting the downward travel of said piston.

`-4. AYdraf-t control for a furnace comprising a draft manipulating device `provided with a Vsubfstantially vertical run,y a reservoir having its bottom connected to the top of asection of `sz'aLidru'r'i and lits top open to atmosphere, =a Yli id medium' partly filling said reservoir the remainder thereofbeingilhledwith atmosphere, a plunger slidable infsaid reservoir and having a -bypassv Yand 'valve to 'per-init said .plunger touni'estrainedly mo'v downwardly through `said liquid medium means itereonhectngsaid plunger With the bottom a sec-tion of said vertical 'immediately 'above said frst section, said plunger and fsaid reservoir being spaced apart to slowly permit the passage of said liquid medium therebetween to retard the downward movement of said reservoir with respect to said plunger until the level of said liquid medium has receded below the top of said plunger whereupon said plunger will be retarded by the passage of air between said plunger and said reservoir and unretarded by said liquid medium, and abutment means for providing an extreme limit of downward movement of said reservoir with respect to said plunger.

5. A draft control for a furnace comprising a draft manipulating device provided with a substantially vertical run, a reservoir having its bottom connected to the top of a section of said run and its top open to atmosphere, a liquid medium partly filling said reservoir the remainder thereof being filled with atmosphere, a plunger slidable in said reservoir and having a by-pass and valve to permit said plunger to unrestrainedly move downwardly through said liquid medium, means interconnecting said plunger with the bottom of a section of said vertical run immediately above said rst section, said plunger and said reservoir being spaced apart to slowly permit the passage of said liquid medium therebetween to retard the downward movement of said reservoir with respect to said plunger until the level of said liquid medium has receded below the top of said plunger whereupon said plunger will be retarded by the passage of air between said plunger and said reservoir and unretarded by said liquid medium, abutment means for providing an extreme limit of downward movement of said reservoir with respect to said plunger, and spring means in said cylinder for urging said plunger downwardly through said liquid medium when the tension on said plunger supplied by said draft manipulating device is released upon said device being movedA tension in said device while said plunger is below the level of said liquid medium, a vertical groove in one of said plunger or reservoir to provide an enlarged space therebetween for the remainder of `the permissible relative travel therebetween while said plunger is above the level of said liquid medium whereby the fiow of atmospheric air between said plunger and reservoir is unrestricted by the incidental clinging of said liquid medium to the surface of said plunger as said plunger and reservoir are relatively moved in said remainder by tension in said device, and a by-pass and valve therefor permitting said liquid medium to freely iiow and allow said plunger to freely move relative to `said reservoir when tension is released in said device.

7. A draft control comprising a draft manipulating device having adjacent sections, a reservoir connected to one of said sections, a plunger connected to the other of said sections, saidv plunger being slidable, within said reservoir between predetermined limits, a liquid medium of density and specific gravity greater than air said reservoir,

partly fillingA said'plunger and reservoir havingV restricted space therebetween whereby the ow of said liquid medium between said plungerand reservoir is retarded as said plunger and reservoir are relativelyl moved by tension in said device while said plunger is below the level of said liquid medium, a vertical groove in one of said plunger or reservoir to provide an enlarged space therebetween for the remainder of the permissible relative travel therebetween while said plunger is above ,the level of saidliquid Vmedium whereby the ow of atmospheric air between said plunger and, reservoir is unrestricted by the incidental clinging, of said liquid medium to the surface of vsaid plunger as said plunger and reservoir are relatively moved in saidremainder by tension in said device, a bypass and valve therefor permitting said liquid medium to freely iiow and allow said plunger to freely move relative to said reservoir when tension is released in said deviceZ and refsill ient means carried in said cylinder for urgingsaid last mentioned relative movement. y

f WILLIAM G. JOHNSON.

REFERENCES CITED VThe following references are of record in thele of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,570,558 October 9, 1951 WILLIAM G. JOHNSON It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 8, line 1, strike out partly filling and insert the same in column 7, line 37, after air;

and that the said Letters Patent should be read as corrected above, so that the sa'me may conform to the record of the case in the Patent Office.

Signed and sealed this 29th day of January, A. D. 1952.

[SEAL] THOMAS F. MURPHY,

Assistant Gommsz'oner of Patents. 

